1. Field of the Invention
This invention relates to a detection system that can be used for detecting and possibly identifying persons, cattle or goods moving through a pre-determined zone. Such a system normally comprises a number of gates provided with means for generating a magnetic field, and each forming a detection zone for detecting wafers having electrical oscillating circuits embedded therein. The wafers are carried by the persons to be detected or are attached to the goods to be detected or the cattle to be detected.
2. Description of Prior Art
A disadvantage of prior systems is that, for example, when they are used as anti-theft systems for shops, but also with other applications, the gates should be rather narrow for effective, spatially determined detection. In prior systems, use is made of gates approximately 1 m wide. If wider gates were used, it would be possible for two or more persons to move through the gate at the same time. If one of these persons carries an article provided with a wafer with an oscillating circuit; it is almost impossible to determine which person is carrying the safeguarded article, in other words, the spatial selectivity of the prior systems is poor. Furthermore, relatively narrow gates form obstacles in passageways, such as entries and exits of shops, which may be objectionable in connection with fire regulations.